Fermionic quantum computation with Cooper pair splitters

TL;DR

This paper introduces a practical scheme for a universal fermionic quantum computer using quantum dots and superconducting elements, with designs that mitigate charge noise to enhance coherence.

Contribution

It proposes a novel implementation of fermionic quantum computation with tunable quantum dot devices and analyzes noise resilience strategies.

Findings

Demonstrates control of Cooper pair splitting and cotunneling for quantum gates

Identifies a charge-neutral sweetspot to reduce charge noise decoherence

Compares two device designs and discusses experimental challenges

Abstract

We propose a practical implementation of a universal quantum computer that uses local fermionic modes (LFM) rather than qubits. The device layout consists of quantum dots tunnel coupled by a hybrid superconducting island and a tunable capacitive coupling between the dots. We show that coherent control of Cooper pair splitting, elastic cotunneling, and Coulomb interactions allows us to implement the universal set of quantum gates defined by Bravyi and Kitaev. Due to the similarity with charge qubits, we expect charge noise to be the main source of decoherence. For this reason, we also consider an alternative design where the quantum dots have tunable coupling to the superconductor. In this second device design, we show that there is a sweetspot for which the local fermionic modes are charge neutral, making the device insensitive to charge noise effects. Finally, we compare both designs and their experimental limitations and suggest future efforts to overcome them.